著者

青木 慶

出版者

日本マーケティング学会

雑誌

マーケティングジャーナル (ISSN:03897265)

巻号頁・発行日

vol.39, no.2, pp.22-35, 2019-09-27 (Released:2019-09-27)

参考文献数

34

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本稿の目的は,企業とユーザーの価値共創のさらなる発展に向けて,ユーザーの参画およびアイデア共有を促す,有効なインセンティブを明らかにすることである。Appleが運営する教育者のユーザーコミュニティを事例研究の対象とし,17名のコミュニティメンバーにインタビュー調査を行った。その結果,単なるユーザーではなく,有用なイノベーションを行う可能性の高い「リードユーザー」を組織化することで,コミュニティ自体が有効なインセンティブとして機能しうることが示された。Appleではコミュニティメンバーに外発的・内発的なアプローチを行い,コミュニティにおける活動を活性化し,ユーザーと「教育の革新」という社会的な価値を共創していることが明らかになった。

著者

青木 慶 河内 まき子 持丸 正明

出版者

バイオメカニズム学会

雑誌

バイオメカニズム学術講演会予稿集

巻号頁・発行日

vol.28, pp.113-116, 2007-11-10

被引用文献数

1

著者

青木 慶 山崎 信寿 井上 剛伸 山崎 伸也 三田 友記

出版者

バイオメカニズム学会

雑誌

バイオメカニズム (ISSN:13487116)

巻号頁・発行日

vol.17, pp.217-226, 2004 (Released:2005-04-15)

参考文献数

9

被引用文献数

2 1

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This paper describes the optimization of hip joint characteristics of a hip disarticulation prosthesis. We attempted to optimize the characteristics for improved ability to walk using our passive walking model, which can walk by utilizing mechanical properties of rigid body segments and joint resistance.In order to understand how the hip disarticulation prosthesis gait is performed, we interviewed two hip disarticulation prosthesis users. The interviews showed that practical gait in daily life is different from the gait at a training stage. These two types of gaits were named “practical gait” and “training gait.” Users indicated that the training gait velocity was slower than that of the practical gait. Moreover, in the practical gait the heel contact on the prosthesis side was more natural in comparison with the training gait.Gait measurements showed that the lumbar angle pattern has rapid extension and lateral bending involving the swing prosthesis in training gait. Step length on the sound side is in agreement despite the different types of gait. In practical gait, step length on the sound side agrees with that on the prosthesis side. Gait velocity in practical gait compared with training gait was 28% faster with subject 1 and 7% faster with subject 2. Therefore, practical gait has an improved gait velocity by swinging the prosthesis, as step length on each side is the same. Motion of prosthesis is achieved not by sound lower extremities but by lumbar flexion, extension, and lateral bending. Furthermore, practical gait reduces lumbar motion as much as possible, and reduces muscle force around the lumbar area.We developed a passive swing model by applying the above characteristics. This model is composed of eight rigid segments: upper torso, pelvis, upper extremities, thigh, shank-foot. Each joint has passive resistance by ligament. The sound hip and lumbar joint have active moments by muscle, which were obtained from measurement. The objective function for practical gait is defined by the following parameters: (1) difference of each step length, (2) amplitude of active moments, (3) difference of cycles between gait patterns and active moments. As these parameters are minimized, postures of segments, translational velocity, angular velocities and cycle, and amplitude of active moment are recorded. In comparison of subjects, calculated motion patterns on the prosthesis side were well in agreement, so this model is available to estimate hip joint characteristics.When this model simulates a condition of the current hip elastic characteristic weakened by half, the gait velocity is 6% faster and amplitude of lumbar lateral bending moment is reduced 26%. For this reason, weakening current elastic characteristics around the hip joint can easily control the swing of the prosthesis. As a result, adjustment of the hip elastic characteristic can improve the walk capability.

著者

青木 慶 山崎 信寿

出版者

バイオメカニズム学会

雑誌

バイオメカニズム

巻号頁・発行日

vol.14, pp.59-68, 1998

被引用文献数

4 12

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Joint resistance is the passive torque exerted by viscoelastic tissues such as ligaments, capsules, tendons, and muscles around the joint. The main function of joint resistance is restriction of the range of motion. However its positive role for human bipedal walking has not been clarified. In this study, we developed a three-dimensional passive-walking model that can walk on an inclined plane by utilizing gravitational force and joint resistance. By using the model, we can easily observe the influence of joint resistance on walking. The model consists of eleven rigid segments; head, chest, pelvis, upper arms, forearms, thighs, and shank-foot segments. The foot part is modeled with a semicircular plate and can roll over the slope. The joint resistance is approximated with a nonlinear viscoelastic torque element, which can prevent hyperextension and hypertwist of the joint. In order to prevent the knee joint from flexing at heel contact, minimum active torque exerted by the knee extensor during the first stance phase is measured from real walking and approximated as a nonlinear viscoelastic element. If the passive model is placed on a slope, the supporting leg naturally rotates down on the semicircular foot, and the other leg swings forward until it reaches to the slope surface. This motion is repeated to generate walking. Initial conditions of the segment angles, angular velocity, and walking velocity are determined by an optimization so as to minimize the difference in walking pattern between the first and second steps. For evaluation of the model, we calculated the passive walking with actual and artificially restricted knee properties, and these agreed well with actual walking patterns. We simulated passive walking patterns by measured changes in the knee and hip joint resistances and also the range of joint motion. Body proportions were also changed from those of a baby to those of an adult. These simulated results show the following roles and characteristics of the joint resistance by passive tissues: 1) knee joint resistance is important when active torque is applied and at the end of the stance phase, and hip joint resistance acts during only the last stance phase; 2) the supporting leg behaves like a stick during the first half stance phase; 3) elastic energy is charged up in the hip and knee joint by extension action around the ankle joint; 4) the charged energy is released at the swing phase, and the thigh swings forward and shank swings upward; 5) joint motions are not greatly affected by alternation of joint resistance; 6) the walking cycle lengthens if the resistance is weakened or the joint range becomes wider; 7) the strength of joint resistance relates to the body proportions, namely knee joint resistance relates to shank length, and hip joint resistance relates to the inertial moment of the leg; 8) the active torque around a knee joint has less influence in passive walking; 9) the patterns of joint resistance torque are similar to those of muscular torque in real walking; and 10) joint resistance saves walking energy. Consequently, we can understand that joint resistance is adapted to the body proportions and bipedal walking. This fact is useful in restoring fossil humans and their locomotion.